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Hf2Au crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two Hf2Au sheets oriented in the (0, 0, 1) direction. Hf is bonded in a 12-coordinate geometry to four equivalent Au atoms. All Hf–Au bond lengths are 2.99 Å. Au is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.
Hf3Au is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hf is bonded in a distorted square co-planar geometry to four equivalent Au atoms. All Hf–Au bond lengths are 3.08 Å. Au is bonded to twelve equivalent Hf atoms to form a mixture of face and corner-sharing AuHf12 cuboctahedra.
AuHf is gamma CuTi structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Hf is bonded in a 10-coordinate geometry to six equivalent Au atoms. There are a spread of Hf–Au bond distances ranging from 2.86–3.30 Å. Au is bonded in a 10-coordinate geometry to six equivalent Hf and four equivalent Au atoms. All Au–Au bond lengths are 2.98 Å.
Au2Hf crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Hf is bonded in a distorted q6 geometry to ten equivalent Au atoms. There are eight shorter (2.93 Å) and two longer (2.94 Å) Hf–Au bond lengths. Au is bonded in a 10-coordinate geometry to five equivalent Hf atoms.
HfAu3 is beta Cu3Ti structured and crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. Hf is bonded to twelve Au atoms to form a mixture of face, edge, and corner-sharing HfAu12 cuboctahedra. There are a spread of Hf–Au bond distances ranging from 2.89–3.05 Å. There are two inequivalent Au sites. In the first Au site, Au is bonded in a 12-coordinate geometry to four equivalent Hf atoms. In the second Au site, Au is bonded in a distorted see-saw-like geometry to four equivalent Hf atoms.
HfAu9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Hf4+ is bonded to twelve Au+0.44- atoms to form HfAu12 cuboctahedra that share corners with six equivalent AuAu12 cuboctahedra, edges with four equivalent HfAu12 cuboctahedra, edges with eight AuAu12 cuboctahedra, faces with two equivalent HfAu12 cuboctahedra, and faces with two equivalent AuAu12 cuboctahedra. There are a spread of Hf–Au bond distances ranging from 2.93–2.96 Å. There are five inequivalent Au+0.44- sites. In the first Au+0.44- site, Au+0.44- is bonded to twelve Au+0.44- atoms to form AuAu12 cuboctahedra that share corners with six equivalent AuHf3Au cuboctahedra, edges with four equivalent HfAu12 cuboctahedra, edges with eight AuAu12 cuboctahedra, and faces with eight AuAu12 cuboctahedra. There are eight shorter (2.96 Å) and four longer (2.97 Å) Au–Au bond lengths. In the second Au+0.44- site, Au+0.44- is bonded to twelve Au+0.44- atoms to form AuAu12 cuboctahedra that share corners with three equivalent HfAu12 cuboctahedra, corners with five AuAu12 cuboctahedra, edges with two equivalent HfAu12 cuboctahedra, edges with six AuAu12 cuboctahedra, a faceface with one HfAu12 cuboctahedra, and faces with eight AuAu12 cuboctahedra. There are a spread of Au–Au bond distances ranging from 2.94–3.00 Å. In the third Au+0.44- site, Au+0.44- is bonded to three equivalent Hf4+ and one Au+0.44- atom to form distorted AuHf3Au cuboctahedra that share corners with fourteen AuAu12 cuboctahedra and edges with three equivalent AuHf3Au cuboctahedra. In the fourth Au+0.44- site, Au+0.44- is bonded in a distorted single-bond geometry to one Hf4+ and six Au+0.44- atoms. In the fifth Au+0.44- site, Au+0.44- is bonded in a distorted L-shaped geometry to two equivalent Hf4+ and three Au+0.44- atoms.
Hf7Au10 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are four inequivalent Hf sites. In the first Hf site, Hf is bonded in a 10-coordinate geometry to ten Au atoms. There are a spread of Hf–Au bond distances ranging from 2.93–3.01 Å. In the second Hf site, Hf is bonded in a distorted body-centered cubic geometry to eight Au atoms. There are four shorter (2.83 Å) and four longer (2.84 Å) Hf–Au bond lengths. In the third Hf site, Hf is bonded in a 8-coordinate geometry to eight Au atoms. There are a spread of Hf–Au bond distances ranging from 2.84–2.89 Å. In the fourth Hf site, Hf is bonded in a 7-coordinate geometry to seven Au atoms. There are a spread of Hf–Au bond distances ranging from 2.90–3.00 Å. There are three inequivalent Au sites. In the first Au site, Au is bonded in a 6-coordinate geometry to six Hf atoms. In the second Au site, Au is bonded in a 10-coordinate geometry to five Hf atoms. In the third Au site, Au is bonded in a 6-coordinate geometry to six Hf atoms.